Active pixel sensors and other image sensors often have a trade-off between size of pixels in the sensor and the abilities of the sensor. More pixels may be more desirable, since it may enable the system to acquire light with a higher resolution. However, more pixels can only be added by either increasing the size of the substrate on which the pixels are located, or by reducing the size of the pixels themselves. In order to accommodate this trade-off, it may become important that the pixels be efficiently placed on the substrate. The fill factor refers to the way in which the pixels are placed on the substrate.
Different pixel arrangements may have advantages in different situations. For example, active pixel sensors may be used for image acquisition, moving picture acquisition in either interlaced or non-interlaced format, and/or in freeze frame operations.
The present application teaches dual use of photodetectors on a substrate. Photodetectors often accounts for one of the largest real estate use on the pixel substrate. In an embodiment, a plurality of the photodetectors are associated with structure that allows the single photodetector to be used with several different pixels.